The art of the present invention relates to automotive engine crankshaft bearing caps in general and more particularly to an improved internal combustion engine bearing splay cap which uniquely registers with the engine block whereby a phenomena called “cap chatter” is minimized.
Internal combustion engines in part comprise an engine block having a crankshaft which is rotatably mounted within main bearings (traditionally a split sleeve bearing shell lined with a babbitt material). As aforesaid, the main bearings are usually split into halves and further mounted within the bearing seats formed between the engine block and the main bearing caps. That is, conventional engine blocks typically have half of the seat formed within the engine block base and half of the seat formed within each main bearing cap. Each of said seats are typically notched in order to secure and prevent spin of said main bearings via a protrusion on each of said bearing shell halves. The conventional engine block half seat also has an oil port which provides a pressurized oil flow through a hole within the main bearing half within the engine block half seat. When the main bearing caps are positioned and bolted onto and with said engine block base, a complete bearing seat is formed with the crankshaft rotatably held within said split main bearings. A conventional “V” type engine block typically contains one more bearing seat than the number of cylinders divided by two.
Conventional main bearing caps are typically machined castings held with the engine block via two bolts or studs through separated mounting holes on each side of the half seat. That is, each bolt fits through the cap and threads into a corresponding threaded hole within the engine block. Each conventional cap typically registers or positions via a shoulder on each side (outside) of said cap. That is, a conventional engine block typically has a recessed channel machined to a width substantially representing the shoulder-to-shoulder distance of said cap. The cap intimately fits within this channel and thereby is positioned or registered. When registered, the half seats of the block and cap form an optimum and aligned full bearing seat, especially after the seats are bored.
Modern internal combustion engines obtain significantly more horsepower from a smaller displacement. The increased efficiency provided by a smaller displacement engine is highly desirable for contemporary vehicle propulsion. Unfortunately, the increased stresses associated with the aforesaid requires improvements in conventional engine components, especially main bearing caps, in order to provide the durability and reliability of predecessor low power designs. Although sufficient for low power output operations, conventional main bearing cap configurations present significant durability and reliability issues when utilized with modern high power engines. When utilized with a higher engine power output, conventional caps tend to lose the aforesaid register. That is, the bearing seat halves tend to deform and no longer form an optimum circular full bearing seat. When higher power is applied, conventional cap seat walls tend to deform and the wall sides near the engine block tend to move toward the crankshaft centerline. (i.e. inward) This deformation is especially possible within the prior art since the there is no registration structure prohibiting cap deformation inward toward the crankshaft centerline. Main cap register failure typically creates what is known in the art as a main cap chatter. Main cap chatter has serious operational effects on an internal combustion engine including but not limited to premature main bearing and crankshaft failure, reduced efficiency, reduced output power, reduced oil pressure, and an introduction of harmful crankshaft harmonics.
The present art main cap represents a uniquely splayed cap in conjunction with a uniquely modified engine block which forms the apparatus and method of installation and use, all of which uniquely register in a fashion which minimizes the possibility of cap chatter or deformation. The term “splayed” means to be spread out or further apart. Splayed main bearing caps are spread further at the interface with the engine block. In short, a splayed cap is wider than a conventional cap and typically has four instead of two bolts for attachment. Splaying the caps provides superior strength relative to conventional caps, thereby allowing for reliable use within high power output internal combustion engines.
Although splayed caps have been found within the prior art, said prior art splayed caps register as conventional caps and exhibit the registration inadequacies associated with the prior art. That is, they only position or register with the engine block at the outside of the cap via a shoulder on each side. Since the splay cap is substantially wider than the conventional cap, registration of the prior art cap occurs over a wider distance than desired. That is, since the shoulder to seat distance for a conventional cap may be approximately an inch, for a prior art splay cap, the shoulder to seat distance is near three inches. Since the metallic cap material (typically a high carbon steel) has elastic properties for the same modulus of elasticity (Young's modulus) and applied crankshaft force, the prior art wider registering splay cap will allow for a greater movement between the cap and seat halves. (i.e. greater strain for equivalent stress) Unfortunately, this movement results in the same undesirable cap chatter and deformation which is present within conventional main bearing caps. Also, as with conventional caps, there is no structure to prohibit inward movement of the cap seat walls.
The present art splay cap represents a uniquely registered splay cap apparatus and method of manufacture, installation, and use which provides the benefits of the prior art splay cap strength while further registering the cap much closer to the bearing seat in a form which minimizes bearing seat wall movement in any direction. The present art minimizes the deleterious effects of material elasticity over greater distances by utilizing cap slots which intimately mate with uniquely formed engine block protrusions near the bearing seat. The present art thereby provides a more secure lock of the cap into the block and minimizes the ability of the cap to move inward. All of the aforesaid provide greater stability and durability than prior art splay caps.
Accordingly, an object of the present invention is to provide a locking engine splay cap and method of manufacture and use which locks the cap with the block and eliminates the ability of the cap to move inward.
Another object of the invention is to provide a locking engine splay cap and method of manufacture and use which minimizes main bearing seat deformation and cap chatter.
Another object of the invention is to provide a locking engine splay cap and method of manufacture and use which has more cross sectional strength than conventional main bearing caps while providing a registration which minimizes deformation due to material elasticity.
A further object of the present invention is to provide a locking engine splay cap and method of manufacture and use which locks in with the engine block.
A still further object of the invention is to provide a locking engine splay cap and method of manufacture and use which reduces distortion of the main bearing bores by increasing the cap's resistance to closing under high loads.